Q&A - PSLE Math

[Augmum]

enoawng, well said........


Moreover, the person who sets this question is an adult but the person who has to solve it is only a 12 years old kid under short limited time :?:

my gal also tried using the algebra approach, but got 2 variables so she tried substituting this and that.....trying to get something out of it but at the end she also cannot remember what she got. she said she spent the most time cracking this question.

[enoawng]

Augmum:

enoawng, well said........


Moreover, the person who sets this question is an adult but the person who has to solve it is only a 12 years old kid under short limited time :?:

my gal also tried using the algebra approach, but got 2 variables so she tried substituting this and that.....trying to get something out of it but at the end she also cannot remember what she got. she said she spent the most time cracking this question.

My son just skipped this question and I took 10-15 minutes before I realized the variables must cancel out. When I was a teenager I was top of my school in maths;-)

If they want to teach model and heuristic approach then they need to set questions to align with the approach. To teach model/heuristic and to set questions beyond that level is bullsxxx.

My future approach will be to get the child to be very proficient in algebra.

[kiasiparent]

dinoegg:

kiasiparent:

[quote=\"N3SKiasu\"]The Speed question (if my DD remembered correctly):


Mei and Lin take part in a cycling race.
Mei's speed is 20km/h. When Lin travelled half of the distance, Mei was 3.5km in front of her.
Mei reached finishing line at 10.45am.
What time did Lin reach the finishing line?

Similar feedback - paper was tough, finished all but not a lot of time left to check through. Anyway, its over now, just move on and focus on next few papers.

So take the total distance to be 2 units.
When Mei travels 1 unit + 3.5km, lim would have travelled 1 unit.
When Mei travels 2 units + 7km, lim would have travelled 2 units. (just finished the race).

So Mei needs to overshot by 7km.

Time = Distance/Speed = 7/20 hours = 7/20 x 60 = 21 minutes.

Lim needs to run 21 mins more.

10.45 + 16 mins = 11.06am

Personally I still find this question 'unanswerable'.. Lim's speed is definitely slower than Mei's speed. So with the Lim's speed left unknown, how to know when Lim will finish the race? The 21mins is the time for Mei to cover the 7km with speed of 20km/h. So Lim will definitely take more than that. Any smart brains to help me clearing my doubts? :)[/quote]For this question, you have to make one assumption and that is both start off the race at the same start line and at the same time.

Hmmm, in the past, PSLE exams were straight forward and all doubts are cleared before they approved the questions to be set. Now, the questions are deliberately set to make the students think hard.

[gifted_indian]

kiasiparent:

For this question, you have to make one assumption and that is both start off the race at the same start line and at the same time.


Hmmm, in the past, PSLE exams were straight forward and all doubts are cleared before they approved the questions to be set. Now, the questions are deliberately set to make the students think hard.

Indeed. Think too hard under a short time. Do you how many P6 kids had sacrificed their social and quality learning time this year, for MONTHS (some even YEARS), just to realise that their PSLE consists of a bunch of unrealistically set questions?

Yes, I say unrealistic since even most of the GEP kids could not even confirm their answer for the last 4 questions. I mean, up till now, have you heard of any parent or student who have said \"I can confidently score Paper 2 this time\" ?

If you haven't, then I think the setters have gone too far beyond what even the smartest brainiest 12-year-old kid in SG can go. Not a fair test I say.

I won't be surprised if some of our maths whizzes would stop pursuing their interest in the subject altogether after this paper. Have the authorities even thought of it? Is assessment, not interest, the number one thing on everyone's minds in SG?

[Vanilla Cake]

MummyJamie:

Ohh! And for paper one, the second last question, the computer one, what did ya'll get?

I got 100 minutes. Many are saying it's 25.
o_o

PSLE Maths 2009 Paper 1 Q29 (Not in exact words)
6 friends decided to rent computers from 2 to 4.30 pm.While 4 of them were playing, the other 2 would watch.If the cycle continued, how much playtime would each person get?\t

Suggested solution
From 2 pm to 4.30 pm -> 2 h 30 min = 150 min\t\t
4 x 150 = 600 (Total for 4 computers since there were 4 players)\t\t
600 / 6 = 100 min\t\t
Amount of playtime that each person get was 100 min

[justsay]

gifted_indian:

Indeed. Think too hard under a short time. Do you how many P6 kids had sacrificed their social and quality learning time this year, for MONTHS (some even YEARS), just to realise that their PSLE consists of a bunch of unrealistically set questions?


Yes, I say unrealistic since even most of the GEP kids could not even confirm their answer for the last 4 questions. I mean, up till now, have you heard of any parent or student who have said \"I can confidently score Paper 2 this time\" ?

If you haven't, then I think the setters have gone too far beyond what even the smartest brainiest 12-year-old kid in SG can go. Not a fair test I say.

I won't be surprised if some of our maths whizzes would stop pursuing their interest in the subject altogether after this paper. Have the authorities even thought of it? Is assessment, not interest, the number one thing on everyone's minds in SG?

That is absolutely true ! I fully agreed.

[Muffins]

Tang:

Sorry to have mixed up Lin and Mei and confused you as I solved the problem the previous day and I have just completed my SA2.


Let me start all over again.


When Lin cycled from start to mid-point,

Mei completed the same distance + 3.5 km.

To cycle the 3.5 km, Mei took 10.5 min. [3.5 km /20 km/h x 60 min/h]

That is, Mei reached the mid-point 10.5 min earlier than Lin.

Conversely, Lin reached the mid-point 10.5 min later than Mei.


Since for half the distance Lin cycled and both cycling at constant speed, he was 10.5 min slower, so for the whole distance Lin would be 21 min slower than Mei. [10.5 min x 2]

Hence Lin reached the finishing line later than Mei by 21 min, i.e. 11.06 a.m. [21 min past 10.45 a.m.]

Have a nice weekend. Bye.

Wow, Tang, still hard to believe you're only in secondary school. You are one of the best maths sums solvers on this site! Kudos to you!

[Muffins]

Tang:

My answer was to move Lim back to the mid-point, hence Mei also had to be moved backwards corresponding. As timeframe was unchanged, it would mean that Mei would take 10.5 minutes more to travel from where she was moved back to to the mid-point. Hence when Lim had completed the race, she would need a total of 21 minutes to reach the finishing line.



Same as my tutor's solution, Kiasuparent has assumed that Lim had continued with his cycling at the costant speed of 20 km/h. Lim travelled another 21 minutes at 20 km/h before Mei finally finished her cycling. [There was no increase in speed for Lim.]

Hi Tang,
Though your answer is correct, can you shed some light on HOW you know that Lin's speed was (would become) 20km/h, as in the question, they said that their speeds are not changed, and if you draw a timeline, or even look at the question, Lin is ALWAYS slower than Mei. So can you please tell me how both of their speeds are 20km/h if what I said above is true? Thanks.

[Tang]

Removed - housekeeping

[Muffins]

Tang:

Please ignore this posting as I have mixed up Lin and Mei. You may refer to my latest posting or the posting at 1800-teacher. Sorry to have caused the confusion. 一万个对不起.

It's fine, Tang.
Can understand now.
Thanks!